A student investigates the conditions needed for iron to rust. She places an iron nail in each of three test tubes, A, B and C.
Tube A contains distilled water and is open to the air.
Tube B contains water that has been boiled, with a layer of oil on top.
Tube C contains dry air, with anhydrous calcium chloride to absorb water, and is sealed with a bung.
The table shows her results after one week.
| Tube | Conditions | Has the nail rusted? |
|---|---|---|
| A | air and water | yes |
| B | water but no air | no |
| C | air but no water | no |
Use the results to state the two substances needed for iron to rust.
Give the reason why the water in tube B was boiled.
Give the reason why a layer of oil was put on top of the water in tube B.
When iron rusts, it gains oxygen. Name this type of reaction.
Give two methods that are used to stop iron objects from rusting.
42 exam-style questions on Edexcel GCSE Chemistry 6.1 Transition metals, alloys and corrosion, covering 6.1.1 Properties of transition metals, 6.1.2 Corrosion and its prevention, and 6.1.3 Alloys and the uses of metals. Each one has a worked solution and a mark scheme showing where the marks go.